Getting the json array from servlet to javascript variable

Question

I have a java servlet that sends a json object to a jsp page in a javascript variabile with array format.

Here is my servlet ( a part of it):

List<HistoryLeavesScalar> returnedPastInfo = SaveDAO.getPastInformation(username);
JSONArray jsonArray = new JSONArray(returnedPastInfo);
String s = jsonArray.toString();
System.out.println("\n\n"+"JSON ARRAY is :  "+s);

HttpSession session = request.getSession(true);
session.setAttribute("jsonArray",jsonArray); 
this.getServletContext().getRequestDispatcher("/calendar.jsp")
.forward(request, response);

that system.out.print JSON is something like this in my console: [{"endDate":"2017-04-22","req":"2017-04-19","nr":2,"type":"CO","startDate":"2017-04-20","Dep":"2017-04-19"},{"endDate":"2017-04-22","req":"2017-04-20","nr":3,"type":"CM","startDate":"2017-04-20","Dep":"2017-04-19"}]

This Json Array I want to be visible in javascript tag like this in that format only: ( this is calendar.jsp - a part of it)

    <%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> 
    <%@ page import="javax.servlet.jsp.jstl.core.*"%>
    <%@ page import="javax.servlet.jsp.el.*" %> 
    <%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql"%>
<script type="text/javascript">

    var USER_DAYS   =   [
                <c:forEach items="${jsonArray}" var="jsonArray">


                        {
                            id: '${jsonArray.nr}',
                            date: '${jsonArray.req}',
                            title: '${jsonArray.type}',
                            startDate: '${jsonArray.startDate',
                            endDate: '${jsonArray.endDate',
                            allDay: true,
                            className: 'done'
                        }
               </c:forEach>
    ];
</script>

I don't know how to access the values from that json that comes from the servlet in USER_DAYS variable (javascript). How to put the values from json in id, date, title, startDate, endDate.

I don't know if jstl works in a javascript tag. I don't know how to print that values ( whatever they are - it can contain many information, all in that format).

I want to mention that, if I change the javascript variable into somthing like this: it works just fine. But these are values which I have handwritten, but now I want them dynamically...and this information must come from servlet into calendar.jsp.

var USER_DAYS   =   [
      {
          id: 1,
          date: '2017-04-05',
          title: 'CO',
          start: new Date(2017, 3, 5),
          end: new Date(2017, 3, 7),
          allDay: true,
          className: 'done'
      },

Can someone help me?

Just try this in javascript . No need any JSP tags. Directly we can assign model attribute into our js variables. var USER_DAYS = '${jsonArray}'; — Prasath
– Prasath, Commented Apr 25, 2017 at 11:48
Why don't you just save s in session and print it? It's already a correct string representation of the JSON object, no need to create loops and write broken JSON — BackSlash
– BackSlash, Commented Apr 25, 2017 at 11:48

BackSlash · Accepted Answer · 2017-04-25 12:29:18Z

1

You already have it as string:

String s = jsonArray.toString();

Store s in session instead of jsonArray;

session.setAttribute("jsonArray", s);

And print it in the servlet:

var USER_DAYS = ${jsonArray};

MY TEST

Java servlet (with sample data):

bingo.jsp:

HTML result:

Rendered result:

It works.

edited Apr 25, 2017 at 12:29

answered Apr 25, 2017 at 11:50

BackSlash

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9 Comments

Ataur Rahman Munna Over a year ago

I think before you gonna treat USER_DAYS as a json object, you should parse it first, isn't it?

BackSlash Over a year ago

@AtaurRahmanMunna No, because it won't be a string once printed. It will not be printed as string. It will be printed as var USER_DAYS = {[.....]}

Ataur Rahman Munna Over a year ago

can you give me a fiddle?

BackSlash Over a year ago

@AtaurRahmanMunna No, AFAIK there is no online fiddle tool for Servlets supporting JSTL too. You can try on your own though.

BackSlash Over a year ago

@AtaurRahmanMunna This doesn't have the java part, which is required to show you that parsing isn't needed.

|

Anup Singh · Accepted Answer · 2017-04-25 11:57:35Z

0

you can write like this

<script>
    var DAYS = '${jsonArray}';
    if(DAYS.length > 0 ){
    var USER_DAYS = {
            id: DAYS[0].nr,
            date: DAYS[0].req,
            title: DAYS[0].type,
            startDate: new Date(DAYS[0].startDate),
            endDate: new Date(DAYS[0].endDate),
            allDay: true,
            className: 'done'
        };
    }
</script>

answered Apr 25, 2017 at 11:57

Anup Singh

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Comments

Ataur Rahman Munna · Accepted Answer · 2017-04-26 06:43:06Z

You can parse your jsonString to javascript JSON object. Then you want to change some of the object key's of your json object, delete one more extra key [e.g "Dep":"2017-04-19"] and at last want add two key's with values in your final json object.

allDay: true,
className: 'done'

Here is the solution.set data as a json string.

session.setAttribute("jsonArray",jsonArray.toString());

In your jsp

var USER_DAYS = JSON.parse('${jsonArray}');

This will make a JSON object named USER_DAYS. And at last modify your JSON object,

var USER_DAYS = JSON.parse('[{"endDate":"2017-04-22","req":"2017-04-19","nr":2,"type":"CO","startDate":"2017-04-20","Dep":"2017-04-19"},{"endDate":"2017-04-22","req":"2017-04-20","nr":3,"type":"CM","startDate":"2017-04-20","Dep":"2017-04-19"}]');

console.log('Original JSON = ' +JSON.stringify(USER_DAYS));

USER_DAYS.forEach(function(e) {
   e.id = e.nr;
   delete e.nr;
   e.date = e.req;
   delete e.req;
   e.title=e.type;
   delete e.type;
   e.allDay= true;
   e.className='done';
   delete e.Dep;
   
});

console.log('Modified JSON = '+JSON.stringify(USER_DAYS));

See the JSFIDDLE

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